Author: Cody  Friedges,   (Southwest Minnesota State University)

Description:
Chironomidae (Insecta: Diptera) are one of few insect families where temperate species grow, develop, and emerge as active adults during winter in the midwestern United States. These winter-emerging chironomids are long-lived, living on average 18.6 days when held at 6℃ and up to 92 days when exposed to sub-freezing temperatures. Here, we extend previous work, determining the influence that different air temperatures have on longevity and oviposition rates, as well as whether seasonality impacts longevity. Adult chironomids were collected from January to March 2020 from banks of a spring-fed stream in Camden State Park (Minnesota, USA). To determine differential longevity and oviposition rates, the insects were randomly separated into three treatment groups: 2℃,  6℃, and ambient outdoor temperature. Behaviors were monitored daily and recorded until death. Preliminary results indicate that the 2℃ treatment group lived significantly longer (20.1 +/-1.2 days; n = 58), than those in the 6℃ (12.9 +/-0.7 days; n = 80) and ambient air (12.4 +/-1.3 days; n = 24) treatment groups (p < 0.0001). Female oviposition rate was highest in the 6℃ group (57%; n = 36) as compared to the 2℃ and ambient groups (47%, n = 21 and 15%, n = 19 respectively), however these results were nonsignificant (p = 0.065). Findings show that Chironomidae survive longer when exposed to cooler air temperatures, and oviposition rates decrease with fluctuating temperatures. We suggest that Chironomidae exposed to low temperatures potentially exhibit a tradeoff of oviposition rates in favor of longevity.

Category: Scientific Program Abstract > Special Session > CS43 Undergraduate Research Projects